According to the New York Times, the firm's computers were using new trading software that malfunctioned, and over a period of 45 minutes was out of control, buying and selling stocks in over 100 companies.

Knight made the loss when it had to sell the stocks back at a greatly reduced price.

The firm, which is now facing bankruptcy, said the mistake cost it more money than the total revenue it brought in over the last quarter.

It said it is now "actively pursuing its strategic and financing alternatives".

Shares in the company fell 63% of Thursday, to just $2.58 a share.

However it said that none of its customers were affected directly by the bad trades.

The mistake will raise fears over the potential chaos that can be unleashed by automated trades and computerised markets.